The Layer to bottom command lowers the active layer to the bottom of the layer stack. If the active layer is already at the bottom of the stack or if there is only one layer, this menu entry is insensitive and grayed out.
7.20.1. Activating the Command
You can access this command from the image menubar through
Layer → Stack → Layer to Bottom,
or by pressing the Shift key and clicking on the down-arrow icon at the bottom of the Layers dialog.
